Silver halide photographic materials are roughly classified into two types, that is, (1) a type of photographic material which gives a negative image of the original after exposure and development and (2) a type of photographic material which gives a positive image of the original after exposure and development. The present invention relates to the latter type. Silver halide photographic materials which give direct positive image have been well known for many years [see, JP-B-43-13488 (the term "JP-B" as used herein means an "examined Japanese patent publication") and U.S. Pat. No. 3,501,305]. However, silver halide photographic materials which give direct positive image have a problem in that they are sensitized when stored in air after preparation.
Further, there is the problem that they are sensitized during storage until coated photographic materials are made after the preparation of fogged emulsions in the manufacturing process of silver halide photographic materials.
For example, it has been conventional to lower the temperature during the storage of emulsions (for example, emulsions are stored at 5.degree. to 10.degree. C.) to limit any change in sensitivity. However, a change in sensitivity could not be sufficiently limited. Further, a change in sensitivity is apt to be limited when the pH of the emulsions is raised. However, a change in sensitivity cannot be satisfactorily limited by raising the pH either.
Sensitization with the passage of time is larger, the higher the sensitivity of the emulsion used (density is less with lower light).